Generally speaking, the invention relates to the packaging of flat objects formed from at least two sides folded on top of each other.
The products thus have a head end, defined by the edge formed by the folded sides, and a tail end, defined by the free edges of the sides.
For convenience of description, this specification will hereinafter refer to nappies but without thereby intending to limit the scope of the invention, in light of the above.
The packaging of articles of this kind presents several problems, due to the fact that such objects are soft, which means their volume is subject to considerable variations, and asymmetrical (that is, they are flat, with a head end and a tail end, unlike other products, such as rolls of toilet paper which are cylindrically symmetric).
In light of this, prior art apparatuses for packaging nappies (as described, for example, in documents US2007264115, WO2005040020 and U.S. Pat. No. 6,755,008), comprise a bagging machine fed by a conveyor positioned in line with the bagging machine, in order to withdraw groups of nappies from a stacker device and move them in straight line into a preformed plastic bag (held open).
These apparatuses have some disadvantages, however.
One disadvantage is due to the need to feed the device continuously with preformed plastic bags (which also leads to problems caused by static electricity).
Another disadvantage is due to the need to correct the orientation of the nappies as they are conveyed from the stacker device to the bagging machine, by turning them by 180 sexagesimal degrees, to ensure that the nappies are inserted into the bag with the head end facing forwards in the direction of insertion. That is because when the nappies are withdrawn from the stacker device, their head ends face the direction opposite to that in which they are inserted into the bag.
Prior art packaging apparatuses are therefore complex and expensive.
Another disadvantage of prior art nappy packaging systems arises from the need to provide a secondary packaging (that is, a product package consisting of sets of nappies which have already been packaged).
One of the problems with the secondary packaging is to avoiding sealing of LDPE on LDPE which, even if especially surface-treated, does not guarantee that the film of the bag (primary packaging) and the bundle (secondary packaging) will adhere to each other.